1. Field of the Invention
The invention relates to the production of tetramic acid.
2. Background
Tetramic acid is a valuable starting product for the production of beta-lactams, which on their part are used for the production of effective antibiotics (G. Lowe, J. Chem. Soc., Perkin Trans. I, 1973, 2907).
So far advantageous processes for producing tetramic acid are not known to the art. Thus, it is known from Lowe, J. Chem. Soc., Perkin Trans. I, 1973, 2909, the process of converting malonic acid monoethyl ester with glycine ethyl ester in the presence of dicyclohexylcarbodiimide to N-ethoxy-(carbonyl acetyl) glycine ethyl ester, in a further step cyclizing with a base to 2,4-dioxopyrrolidine-3-carboxylic acid methyl ester and finally decarboxylating to tetramic acid. But the basic disadvantage of such process is the necessary, extremely high diluting of the reaction solution in the last step (3.30 g to 2.5 liters means a 0.1 percent solution), which excludes it from being an economical process on a large scale.